Mysterious PSM and ABS

[welshnobby]

The warning lights indicating the PSM is off and also the ABS have lit up. I've taken it to my OPC and they replaced the mass air flow sensor. This worked for a week now they are back on again.

Any suggestions of cause and should i be running the car?

Cheers

WN

[Don]

OK. My first Boxster S did this and Porsche Reading had it in for a fortnight to fix it...

In the end I understood they kept replacing bits off a working car until the problem went away...

BUT. Prior to taking it into the dealership I had been caught out in Portsmouth - long way from home. I called up Porsche Assistance who basically said: if its a red light you'd better get it recovered - if its a yellow its just a warning and you can drive it but it had better be fixed a.s.a.p.

Being the kind of bloke who habitually drives a TVR with no Traction Control or ABS I took the view that provided those systems were fully off line but that the accelerator and brakes would work properly then I could handle that no problem - and drove home, out and about as necessary until Porsche took the car away to be fixed.

Having said that Porsche usually recover cars even with "just" a yellow warning light - depending on what it is. Porsche Assistance gave the confidence to just keep on going for the day...

So - I'd advise giving them a call (if you have it) and confirming what I've said. Otherwise - use as necessary but get it fixed right away...

[welshnobby]

...cheers Don. I do have Porsche assist so i thought i would give them a call. However i turned the ignition to make sure the lights were still on only to find that all was normal again. I took her for a spirited drive and they still stayed off...the mystery continues!

[DaGinge]

Don said:

if its a red light you'd better get it recovered - if its a yellow its just a warning and you can drive it but it had better be fixed a.s.a.p.

Interesting as I believe the light can only be yellow (i.e. there isn't a red one!!!!!)

Have the brakes been bled lately, this can happen if there is air in the system - sounds like the ABS pump needs to be cycled.

[welshnobby]

...air in the system potentially effect the psm too?

[Raven Flyer]

My guess would be a wheel speed sensor. These are common to PSM and ABS.

[DaGinge]

welshnobby said:

...air in the system potentially effect the psm too?

yes, ABS and PSM are inherently linked, so if ABS has a problem then PSM warning light will also come on.

[Don]

DaGinge said:

Interesting as I believe the light can only be yellow (i.e. there isn't a red one!!!!!)

Indeed. But the principle is general. Yellow light on the dash (for anything) means "warning - get this fixed" and a red light means "STOP THE CAR NOW!". I guess this means that car manufacturers consider ABS failure not being something that means you cannot continue your journey.

[cab4man]

Had the same problem with ABS & PSM warning lights on my C4,usually within first mile of travel after start up and usually went away if switch off and start again !! ..... fault eventually traced to stop light switch, hope this helps.